It is well known that vehicle engines are coupled to the exhaust pipe employing a muffler for exhausting the exhaust gas from the vehicle and the coupler acts to absorb and buffer the vibration displacement, impact load or heat deformation.
The coupler on this location should be mounted to absorb engine and road vibrations and displacement. There is a possibility of excessive displacement in any direction, such as tension compression, bending or deflection.
In order to improve absorbing capability of the vibration displacement and maintain airtightness of the coupler of vehicles, the coupler usually includes bellows fabricated from metal.
Various types of the exhaust pipe couplers have been known and one of them is described in U.S. Pat. No. 5,145,215, which shows a flexible coupler apparatus in a compact, simple structure.
In U.S. Pat. No. 5,145,215, both ends of the inner and outer sleeve members, each coupled to the engine and exhaust pipes, in a hollow cylindrical shape are curved on the ends to form rims. Air gaps are shown between rims and inner sleeve member and between inner and outer sleeve members.
A flexible bellows for absorbing the displacement in longitudinal is affixed to the opposite ends of the inner and outer sleeve members.
Caps are outwardly fixed on the ends of the sleeve members and the bellows. A metal wire braid is wrapped around the bellows.
A displacement portion is formed at the intermediate overlapping position of the inner and outer sleeve members, which is elongated and bent, so that the bending displacement in overlapping state of the central axis angle with respect to the exhaust pipe coupler and flexible displacement in longitudinal direction from impact in engine vibration or travelling are absorbed by air gap between the rims and the bellows.
EP 0410089A1 shows a coupler of metal for absorbing expansion or deflection, including bellows. An interlock member is included in the bellows, which functions to absorb expansion or deflection, control displacement within the elastic range, guide the exhaust gas and protect the bellows from exhaust gas of high temperature.
The bellows and braid members thereon are circumferentially affixed to each end by caps together.
One end is coupled to the engine and the other end is coupled to the exhaust pipe for allowing the exhaust gas to pass in the exhaust pipe. Impact or deformation to the engine and the exhaust pipe is absorbed by the bellows and the interlock member.
A fixing means for coupling the opposite ends of the bellows and the interlock member is an important element for determining lifetime of the flexible coupling for exhaust pipe.
The interlock member in spiral may cause problems regarding durability and noise, dependent on the closing method of the opposite ends.
The applicant has suggested an improvement of a flexible tube for coupling exhaust pipe in Korean Utility Model Registration No. 101514, UM Appln. No. 94-36920, including an intermediate member for a fixing means for coupling the opposite ends of the interlock member and the bellows.
The exhaust pipe coupler mainly depends on the metal bellows of good capability to absorb the vibration displacement and keep airtightness. However, excessive displacement and heavy stress on the bellows itself result in low controlling capability.
An outer braid member is mounted outward on the bellows, which functions to keep superior durability in elastic range in each direction with respect to the bellows.
Since the commonly-used one fold outer braid member is made of stainless wire net, it is disadvantageous to insufficiently control excessive power or displacement in tension or compression direction unless the outer braid member is stick to the outer surface of the bellows.
In case that the outer braid member is stick to the bellows, tension forces are controlled but compressive forces are not controlled. This may cause the bellows to be easily worn out depending on the extent of tightness, resulting in short lifetime.